A method and apparatus of converting a series of data words into modulated signals generates for each data word, a number of intermediate sequences by combining mutually different digital words with that data word, scrambles the intermediate sequences to form alternative sequences, translates each alternative sequence into a (d,k) constrained sequence, measures for each (d,k) constrained sequence, not only an inclusion rate of undesired sub-sequence but also a running DSV (Digital Sum Value), and selects one (d,k) constrained sequence having small inclusion rate for recording on an optical or magneto-optical recording medium among the (d,k) constrained sequences having maximum value of running DSV. smaller than a preset limit. Accordingly, efficient DSV control can be achieved for even relatively-long sequences.
Legal claims defining the scope of protection, as filed with the USPTO.
1. A method of converting a series of data words into a modulated signal, comprising the steps of: (a) generating for each data word a number of alternative sequences by combining mutually different digital words with the data word; (b) translating each alternative sequence into a (d,k) constrained sequence according to a predefined coding rate m/n; (c) checking development of digital sum every bit for each translated (d,k) constrained sequence to detect a maximum value in the development of digital sum; and (d) sorting out the translated (d,k) constrained sequences based on whether the maximum value of each sequence exceeds a preset threshold, and selecting one (d,k) constrained sequence for recording onto a recordable medium.
2. The method of claim 1 , wherein the maximum value detected in said step (c) is the largest value in an absolute sense.
3. The method of claim 1 , wherein said step (d) selects one (d,k) constrained sequence with the smallest maximum value in the development of digital sum among the sorted-out sequences.
4. The method of claim 3 , wherein, if there are at least two sequences of which a maximum value in the development of digital sum is smallest, said step (d) selects one (d,k) constrained sequence for recording, based on a number of undesirable subsequences each (d,k) constrained sequence includes.
5. The method of claim 4 , wherein the undesirable subsequences include consecutive long 0 s and/or repetitive Tmin where Tmin is the shortest allowable consecutive 0 s under a given d.
6. The method of claim 3 , wherein, if there are at least two sequences of which a maximum value in the development of a digital sum is smallest, said step (d) selects for recording one (d,k) constrained sequence of which development of a digital sum is smaller at bit end than others.
7. The method of claim 1 , wherein, if there is no sequence of which development of a digital sum does not exceed the preset threshold, said step (d) selects one (d,k) constrained sequence, of which a digital sum at bit end is smallest, among the translated (d,k) constrained sequences.
8. The method of claim 1 , wherein said step (a) further scrambles each combination of a digital word and the data word to form the alternative sequences.
9. An apparatus of converting a series of data words into a modulated signal, comprising: a generator generating for each data word a number of alternative sequences by combining mutually different digital words with the data word; an encoder translating each alternative sequence into a (d,k) constrained sequence according to a predefined coding rate m/n; a judging means checking development of a digital sum every bit for each translated (d,k) constrained sequence to detect a maximum value in the development of digital sum and a digital sum at bit end; and a selecting means checking whether there is at least one (d,k) constrained sequence of which a maximum value in the development of a digital sum is below a preset threshold, and selecting one (d,k) constrained sequence among the translated (d,k) constrained sequences for recording onto a recordable medium based on the detected maximum value if there is, or based on the detected digital sum at bit end if there is not.
10. The apparatus of claim 9 , wherein the maximum value detected by said judging means is the largest value in an absolute sense.
11. The apparatus of claim 9 , wherein said selecting means sorts out the translated (d,k) constrained sequences of which the maximum value is not beyond the preset threshold, and selects one (d,k) constrained sequence with the smallest maximum value for recording onto a recordable medium among the sorted-out sequences.
12. The apparatus of claim 11 , wherein said judging means assigns a penalty to each (d,k) constrained sequence in proportion to a runlength of consecutive 0 s and a runlength of consecutive Tmin s included in the sequence where Tmin is the shortest allowable consecutive 0 s under a given d.
13. The apparatus of claim 12 , wherein, if there are at least two sequences of which a maximum value in the development of a digital sum is smallest, said selecting means selects one (d,k) constrained sequence for recording based on each penalty assigned to each sequence by said judging means.
14. The apparatus of claim 11 , wherein if there are at least two sequences of which a maximum value in the development of a digital sum is smallest, said selecting means selects for recording one (d,k) constrained sequence of which the digital sum at bit end is smaller than others.
15. The apparatus of claim 9 , wherein, if there is no sequence of which development of a digital sum does not exceed the preset threshold, said selecting means selects one (d,k) constrained sequence, of which a digital sum at bit end is smallest, among the translated (d,k) constrained sequences.
16. The apparatus of claim 9 , wherein said judging means further checks whether each (d,k) constrained sequence includes a sync pattern, and wherein said selecting means checks whether there is at least one (d,k) constrained sequence of which development in a digital sum never exceeds the preset threshold after excluding sequences with a sync pattern from the translated (d,k) constrained sequences.
17. The apparatus of claim 9 , wherein said generator further scrambles each combination of a digital word and the data word to form the alternative sequences.
Cooperative Patent Classification codes for this invention. Click any code to explore related patents in that topic.
April 2, 2003
August 17, 2004
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